The present invention is related to aircraft Environmental Control Systems (ECSs) and in particular to a system and method for estimating a fouling condition of a heat exchanger of an ECS
The Environmental Control System (ECS) of an aircraft has two basic functions: i) to provide a fresh cabin air supply, and ii) to deliver thermal control and air pressure to an aircraft cabin in order to provide comfort to crew members and passengers. One component of the ECS is a heat exchanger, which maintains the above two functions by proper cooling of engine bleed air. Aircraft heat exchangers can suffer from performance degradation due to a phenomenon called fouling that occurs when there is unwanted accumulation of external substances, debris, and/or organisms that contaminate the surface of heat exchanger fins. Fouling degrades the performance of the heat exchanger by reducing thermal efficiency, introducing a decrease of heat flux, and adding stress on the cooling mechanism of the heat exchanger. Due to the frequency at which fouling occurs, the heat exchanger is generally scheduled for periodic maintenance, thus incurring economic losses and unwanted interruption of the aircraft operation. Therefore, there is a need to develop a real-time diagnostic tool for detecting and diagnosing fouling of the heat exchanger in-situ.
Since fouling occurs in complex environments where parameters such as altitude levels, ambient temperatures and passenger loads are varying, diagnosing fouling conditions during a maintenance operation on the ground can be difficult.